Straight Pipes With Hi-flo Cats?

[Grayson]

So I have been thinking about an exhaust option for my Denali. A lot of my friends have on their trucks anything from regular Flowmaster 40's to cat back exhausts. Most have been telling me "since you got the 6.2, you should get straight pipes with cats".

 

Now I will tell you I know quite a bit about exhaust systems but not everything. I like the way my friends' 5.3s sound with straight cats, and I know my SD should sound very similar.. just maybe a little louder and/or deeper...?

 

Anyway, back to the question. Would it be perfectly fine for my engine (since I have always been worried about this "backpressure" issue with straight piped exhausts) if I put a Y-pipe (or maybe true dual) with Hi-Flo cats and straight pipes with no muffler?

 

Also, what exactly is "backpressure" and why is it important?

 

 

Thanks

[KENNHON]

So I have been thinking about an exhaust option for my Denali. A lot of my friends have on their trucks anything from regular Flowmaster 40's to cat back exhausts. Most have been telling me "since you got the 6.2, you should get straight pipes with cats".

 

Now I will tell you I know quite a bit about exhaust systems but not everything. I like the way my friends' 5.3s sound with straight cats, and I know my SD should sound very similar.. just maybe a little louder and/or deeper...?

 

Anyway, back to the question. Would it be perfectly fine for my engine (since I have always been worried about this "backpressure" issue with straight piped exhausts) if I put a Y-pipe (or maybe true dual) with Hi-Flo cats and straight pipes with no muffler?

 

Also, what exactly is "backpressure" and why is it important?

Well, back pressure is just what you would think-pressure builds in pipes[anexcellent example is a Top/Fuel dragster... Stright pipes,but pipes would have to be 3 FEET in diameter where there would be LESS resistance-there is the valves[2" in a race hemi]and as one can imagine not all exhaust air can go out the port[you are talking1,000 hp PER CYLINDER]... so pressure builds QUICKLY.... but as tuners found long ago--- you can use it to advantage in your engine by having headers[i have Doug's Tri-Wye long tube headers[454 Vortec].. These time the exhaust pulse to cause a vacuum behind each stroke of exhaust-this vacuum 'pulls the next cylinder's exhaust down-stream... now when this pulse gets to your 'cats' pressure builds again [Resistance in catalysts]-NOT as much as a muffler[loudness equals plus or minus pressure].

 

I have used true dual 2 1/2" straight pipes after cats for 11 years ... But, for my money, Dodge cats have best sound w/o mufflers

 

Thanks

[Jennabear]

Just a heads up on your stock cats, they are already hi-flow, no reason to buy new ones.

[vikinghogue]

running true duals will actually hurt it and the sound because the driver side has to be ran on the passenger side too and that will make the driver side pipe around 4 or 5 feet longer. but the stock cats are pretty high flow but catco makes a direct replacement that is suppose to be good. and back pressure is important because so your engine runs right. but my truck has no muffler and it runs fine it didnt hurt my mpg

[05silvycrew]

straight pipes won't hurt your truck at all.

 

think about it...Magnaflow uses 3" mandrel bent tubing with a straight through muffler (3" core). the only backpressure or flow difference between what they're selling (for upwards of $400-500 I might add) and straight pipes is generated with the tiny perforations within the core of the muffler! If they market that little backpressure, and it's proven as a performance exhaust, then straights aren't going to hurt anything.

 

Now noise control will be a whole different topic entirely!